We are operating in our daily use, large number of electronic platforms that need to be fed with inputs.
Among these electronic devices with displays, we have desktop computers, laptops, TabletPCs, PocketPCs, televisions, cellular phones and the like.
In order to operate/interact with the above devices, a large number of input devices have been invented. Among these devices we have the mouse, trackball, keyboards, remote controllers, active and passive styluses that interact with the screen without having to touch it, resistive screens that need to be touched in order to get the inputs, sensors outside the screen to detect the move of an input device like a stylus, styluses that detect electro-optical wise a pattern imprinted in the screen or on the background of the displayed information etc.
The above input devices can be partitioned in several ways, the first is the partition between absolute and relational devices.
The absolute devices work on the screen itself and include the styluses (active, passive), resistive screen, imprinted pattern and the ones that are being inspected by other outside sensors.
The relational input devices where each movement is relative to the current position and not an absolute position includes the mouse, trackball, keyboard, part of the remote controllers (navigation in equipment menu) etc.
The above input devices can be further partitioned into two other major groups, the first, is the group which doesn't interact directly with the screen and includes the mouse, trackball, keyboard and the remote controller. The second is the group that directly interacts with the screen and is further partitioned into three subgroups:                1. The first subgroup is the one that has built into the screen sensors/elements and includes devices like the passive and active stylus and the resistive screens. For example, such type of devices is disclosed in U.S. Pat. No. 6,118,435 (Fujita, et al.). The patent discloses A display unit with touch panel includes a press detection switch for detecting a press on a touch panel at a pressure exceeding a predetermined level so as to output a press detection signal, a driving-signal generating circuit responding to the press detection signal to generate a driving signal, a driving portion actuated by the driving signal to drive the touch panel into displacement thereby providing an operator with a tactile feedback, and an AND circuit for outputting an AND signal upon receipt of both of a coincidence detection signal from a coincidence detecting circuit and the press detection signal from the press detecting switch, and a gate circuit for inhibiting a passage of the operated-position signal from the operated-position detecting circuit when the AND signal from the AND circuit is not supplied and permitting the passage of the operated-position signal when the AND signal from the AND circuit is supplied. The display unit with touch panel ensures the prevention of operation errors caused by the operator merely sliding his finger on the touch panel or accidentally touching the touch panel.        2. The second subgroup is the one where outside sensors inspect the movement of the input device and includes sensors like cameras and ultrasonic sensors. Such device is disclose in U.S. Pat. No. 6,760,009 (Omura, et al.) where, the coordinate-position inputting/detecting device comprises a lighting device for emitting light into an entry area into which an arbitrary pointing body is inserted to perform an entry operation. At least two image pickup devices are provided with a pre-specified space therebetween on a peripheral section of the entry area for picking up images of the pointing body illuminated by the light from the lighting device. Position on the CCD of the image pickup devices where an image of the pointing body is formed is obtained according to output from each of the image pickup devices. Coordinates of the position of the pointing body in the entry area are calculated from these positions.        3. The third subgroup is the one that calculate the input device location by interpreting a pattern imprinted into the screen. This type is sometimes being augmented with other sensors like gyroscopes and accelerometers. U.S. Pat. No. 7,009,594 (Wang, et al.) describes a universal input device. The universal input device provides a common user interface for a variety of different computing platforms including printed documents. Using the present system, one may use the universal input device to control various computing devices as well as capture handwritten electronic ink and have the electronic in be associated with new or stored documents. The technology is based on an imprinted in the screen pattern that can be inspected with UV camera.        